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Satellites & Platforms

Orbits and platforms are not implementation detail. They are the constraint layer.

What Belongs Here

<ul><li>Orbits, revisit, coverage, tasking vs archive</li><li>Platform constraints that shape latency, availability, and product quality</li></ul>

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Sentinel-2 SAT-002 Sentinel-2 is a pair of optical satellites operated by the European Space Agency (ESA) as part of the Copernicus Earth observation programme. Each satellite carries a Multispectral Instrument (MSI) that captures images in 13 spectral bands — from visible light through near-infrared to shortwave infrared — at resolutions of 10, 20, and 60 meters. With two satellites in orbit (Sentinel-2A and 2B), the combined revisit time is approximately 5 days at the equator and 2-3 days at mid-latitudes. The data is free and open access. Sentinel-2 is the most widely used optical satellite for land monitoring, agriculture, forestry, water resources, and disaster response worldwide. Latency: From Orbit to Application COM-001 Latency in satellite systems is the total time between a sensor observing something on Earth and that observation becoming usable information. It is not one delay — it is a chain of them. Propagation through space, queuing at ground stations, decryption, format conversion, atmospheric correction, reprojection, tiling, indexing, and delivery. Some links are governed by physics and cannot be shortened. Others are engineering choices. Understanding where latency lives determines what questions you can answer with the data. A flood map delivered in 15 minutes can direct evacuations. The same map delivered in 48 hours is a historical record.

Key Concepts

Revisit is not real-time
Revisit period defines observation frequency, not responsiveness.
Tasking changes the contract
Tasking introduces scheduling, priority, and new failure modes.
Ground segment dominates time
Time-to-data is usually dominated by ground segment, not orbit.

All Entries

Sentinel-2 SAT-002 Sentinel-2 is a pair of optical satellites operated by the European Space Agency (ESA) as part of the Copernicus Earth observation programme. Each satellite carries a Multispectral Instrument (MSI) that captures images in 13 spectral bands — from visible light through near-infrared to shortwave infrared — at resolutions of 10, 20, and 60 meters. With two satellites in orbit (Sentinel-2A and 2B), the combined revisit time is approximately 5 days at the equator and 2-3 days at mid-latitudes. The data is free and open access. Sentinel-2 is the most widely used optical satellite for land monitoring, agriculture, forestry, water resources, and disaster response worldwide.

Coming Next

Ground stations & contact windows, Tasking vs archive, Onboard processing and compression

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Communication & Infrastructure Sensors & Physics
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